1. Field of the Invention
The present invention relates to a machine tool numerical control unit for assisting in enhancing the efficiency of work by estimating and notifying a worker beforehand of scheduled work times of day for setup change, chip ejection, periodic inspection, etc., in, for example, a labor-saved, machining work site where one worker operates a plurality of machine tools.
2. Description of the Background Art
In FIG. 13, a flowchart is illustrated which concerns the processing of a programmable controller having conventional clock function as disclosed in Japanese Patent Publication No. 139802 of 1986. This flowchart is for processing data that concerns the timing of a machining operation and, in particular, concerns the identification of any of several steps in a machining cycle and the storage of times related to the spindle operation. First, in step S10, machining is initiated at the start of the machining cycle and then a determination is made as to whether the machine cycle start command is ON (step S11). If it is ON, in step S12, a current time of day (TOD) is read and stored as the machining cycle start time of day in a current time memory (CTM), and the processing ends. If the cycle start command is not ON as determined in step S11, a determination is made in step S13 as to whether a machining end command (M02) has been issued by the machining program. When the M02 command has not been issued, a determination is made at step S15 as to whether the spindle is then to be actuated by the machining program. If actuation is to be made as determined at step S15, the current time of day (TOD) is stored as a spindle actuation start time of day in a spindle memory (SPM) at step 16 and the processing ends. When the result of the determination in step S15 is that actuation is not to be made, a determination is made at step S17 as to whether the machining by the spindle is finished and the machining program has given a spindle-stop command. If no such command is given, the processing ends,
If the spindle stop command has been given as determined at step S17, a resultant spindle operation time (SAM4) is calculated by subtracting the time of day previously set in the SPM from the current time of day, adding that difference to the previous SAM4 value and storing the resultant spindle operation time (SAM4), at step 18. Similarly, when the machining program issues a machining end command M02 and such command is detected at step S13, a resultant machining time (SAM3) is calculated at step S14 and the machining is terminated. The resultant machining time (SAM3) is calculated by subtracting the time of day in the CTM from the current time of day (TOD) and adding that value to the last previously stored value of SAM3, at step S14.
When machining is to be started by a next program and the spindle actuated, similar processing is performed. The resultant machining time SAM3 and resultant spindle operation time SAM4 are newly added and accumulated. Accordingly, by reading the SAM3 and/or SAM4 as required, the accumulated resultant machining time, the resultant machining time on a program number basis, etc., can be obtained. These times can be displayed to an operator in order to ensure ease of resultant machining time management.
FIG. 14A is a processing flowchart and FIG. 14B is a machining result totalization table illustrating an example of a conventional machining result totalizer for use with an NC machine tool disclosed in Japanese Patent Publication No. 312043 of 1988.
The machining result totalization table is made up to allow macro variable values and workpiece names to be cross-referenced. For instance, the macro variable value "1234" corresponds to the workpiece name "PART-A". This machining result totalization table includes a "machining start time of day section", a "machining end time of day section" and a "number of workpieces machined section", wherein the machining start times of day and machining end times of day of workpieces corresponding to the macro variable values, and the total number of workpieces machined, are written.
When machining result totalization processing is started at step S20, the macro variable value is first read and, at step S21, a determination is made as to whether a numerical value is assigned to the macro variable that was read. If a value is not assigned (macro variable=0), the processing returns to the first step S20 and the above operation is repeated. If a value is assigned (e.g., macro variable=1234), the execution progresses to the next step S23, where the macro variable value is checked against the workpiece name on the basis of the machining result totalization table. A machining start time of day is then set at step S24. At the next step S25, the macro variable value is read and a determination is made at step S26 as to whether or not the macro variable read has been cleared. If it has not yet been cleared (e.g., macro variable=1234), the execution returns to the step S26 for reading the macro variable value and the above operation is repeated until it is judged that the macro variable has been cleared (macro variable=0). If it has been cleared, a machining end time of day is set at step S27 and the number of workpieces machined is incremented by 1 at step S28.
The machining result totalization processing is thus terminated at step S29 and the machining result totalization table is filled. This process allows the periods of time required for machining the workpieces, the operation ratio of the NC machine tool, etc., to be totalized directly and exactly.
FIG. 15A illustrates a flowchart of a conventional operation time display system embodiment and FIG. 15B shows the structure of stored operation times of day as disclosed in Japanese Patent Publication No. 31824 of 1988.
As shown in FIG. 15B, the stored structure of the operation times of day comprises a pointer that designates a currently run program number (PR), operation start time of day (MS) and operation end time of day (ME). The data PR, MS and ME may be stored in a table format.
The sequence of processing will now be described according to the flowchart. Referring to FIG. 15A, whether a cycle start has been switched ON or not is first checked at step S30. If it is determined at step S31 that the cycle start has been switched on, the operation start time of day (MS) is stored at step S32 and automatic operation is initiated at step S33. Whether the automatic operation has been finished or not is then checked at step S34. If it has been finished, the operation end time of day (ME) is stored at step S35 and a pointer (PNTR) is incremented by 1 at step S36. Whether the pointer (PNTR) has exceeded a maximum value or not is then checked at step S37. If it has exceeded the maximum value, the pointer is reset to zero at step S38. If it has not exceeded such value, the execution returns to step S31. The above cycle is repeated with the operation start time of day (MS) and the operation end time of day (ME) stored and displayed.
The above processing permits the operator to understand the machine operation status sufficiently so that production control, process control, etc., at a plant can be conducted.
FIGS. 16A and 16B comprise a processing flowchart of a conventional numerical control unit equipped with maintenance time warning means, as disclosed in Japanese Patent Publication No. 62441 of 1985.
Assume that the periodic inspection time of the numerical control unit is set in a timer T1, the maintenance time, e.g., replacement or inspection time, of specific parts of the numerical control unit is set in timers T2 and T3, and the periodic inspection time and overhaul time of a machine controlled by the numerical control unit is set in timers H1 and H2, respectively.
When the numerical control unit is then powered up at step S40, the timers T1, T2 and T3 count up at their respective predetermine cycles, as shown at Steps S41, S42 and S43 of the processing flowchart in FIG. 16A. In addition, while the machine is driven, as determined at step S44, the timers H1 and H2 count up at their predetermined cycles in Steps S45 and S46. In this manner, the timers T1, T2 and T3 count up while the numerical control unit is operating and the timers H1 and H2 count up while the machine to be controlled is driven.
In the meantime, as shown in FIG. 16B, following a start at step S47, whether the timers T1, T2, T3, H1 and H2 have reached their set values or not is detected at their predetermined cycles as seen at Steps 48A-48E, and any set value reached is displayed and an alarm is issued at Steps 49A-49E.
For example, when the periodic inspection time of the numerical control unit is reached, the timer T1 reaches or exceeds its set value, a message describing the periodic inspection time is issued and warning is displayed. After periodic inspection is performed according to the periodic inspection time information provided by the numerical control unit, the timer T1 is cleared to zero again and the next periodic inspection time is set from a manual input device. The maintenance period warning thus displayed provides ease of maintenance control.
FIG. 17A is a flowchart illustrating part of the processing performed by a conventional numerical control unit equipped with a periodic maintenance message displaying function and a memory map for the storage contents thereof, as disclosed in Japanese Patent Publication No. 241805 of 1986.
FIG. 17B illustrates the memory map showing the storage contents of a nonvolatile memory. As shown therein, the nonvolatile memory includes areas #A1-#An each of which has seven addresses, and areas #C1-#Cn which store data to be displayed. First, addresses of the areas #A1-#An (address a in the area #A1) store data indicating a year among the year, month and day on which maintenance should be performed, second addresses (address a+1 in the area #A1) store data indicating a month among the year, month and day on which maintenance should be performed, third addresses (address a+2 in the area #A1) store data indicating a day among the year, month and day on which maintenance should be performed, fourth addresses (address a+3 in the area #A1) store data indicating a year among the year, month and day indicating a maintenance interval, fifth addresses (address a+4 in the area #A1) store data indicating a month among the year, month and day indicating the maintenance interval, sixth address (address a+5 in the area #A1) store data indicating a day among the year, month and day indicating the maintenance interval, and seventh addresses (address a+6 in the area #A1) store the area numbers of the areas #C1-#Cn storing data to be displayed. The data stored in the areas #C1-#Cn are the maintenance instructions such as "CHANGE THE BATTERY" and "LUBRICATE".
The flowchart in FIG. 17A shows part of the processing, which begins when the numerical control unit is powered up at step S50. First, at step S51 time of day (power-on year, month and day) is read from a clock, the year data among the read time of day is stored into address B, the month data into address B+1, and the day data into address B+2. Then, at step S52, a counter value N of an internal software counter is set to "0" and the operation of (A=a+7 * N) is performed at step S53 in order to find the first address of the area to be referenced. Since N is "0" in this case, A=a which is the first address of the area #A1.
Then a comparison is made at step S54 between the maintenance year, month and day stored in the addresses A, A+1 and A+2 and the power-on year, month and day stored in the addresses B, B+1 and B+2 in order to determine whether the clock is past the maintenance year, month and day. It should be noted that if the maintenance year, month and day match the power-on year, month and day, it will be determined that the clock is past the maintenance year, month and day. When it has been determined that the clock is past the maintenance year, month and day, area number j stored in the address A+6 is read, and maintenance data stored in area #Cj corresponding to said area number j is then read and displayed at step S55 as the maintenance instructions associated with the area #A1. On the other hand, when it has been determined that the clock is not past the maintenance year, month and day, no operation is performed and the processing moves on to step S56, wherein the count value N of the internal software counter is incremented by 1. Here, N is set to "1". Whether the count value N of the internal software counter is n (n indicates the number of areas) or not is then determined at step S57. If N is not n, the processing returns to perform the operation of (A=a+7 * N) at step S53. In this case, since N is "1", A=a+7 which is the first address of the area #A2. A comparison is then made between the maintenance year, month and day stored in the addresses A, A+1 and A+2 and the power-on year, month and day stored in the addresses B, B+1 and B+2 in order to determine whether the clock is past the maintenance year, month and day, and the processing as described above is performed according to the determination result. When the aforementioned processing is performed up to the area #An, N is set to n and the processing advances to step S58. Briefly, the above described processing displays the item(s) of maintenance to be performed on that day.
The operator then carries out maintenance work corresponding to the maintenance item(s) displayed. When the maintenance work is over, the operator enters a command which indicates that the maintenance work is over. On detection of the maintenance termination at step S58, the numerical control unit terminates the processing at step S60. The termination occurs after rewriting at step S59 that data indicating the maintenance year, month and day stored in the first to third addresses of the areas #A1-#An, on the basis of the data indicating the maintenance intervals stored in the fourth to sixth addresses of the areas #A1-#An.
Automation is the best way to achieve labor saving at a plant. However, setup work (such as workpiece installation, centering, tool preparations, etc.), in-machining and post-machining work (such as chip ejection, workpiece cleaning, measurement, workpiece removal, etc.) and machine inspection and maintenance work include many areas which must rely on manpower.
Therefore, labor saving is achieved by making one worker responsible for a plurality of machine tools, who finishes setup on one machine tool and effects its automatic start, then begins the setup of another machine tool. In this case, the worker maps out a work schedule, estimating manual work time of day for each machine from experience. In addition, special considerations are generally given to a machine layout so that the worker may supervise the progress of machining. Accordingly, the number of machine tools which one worker can be in charge of is smaller than that of machine tools calculated from the number of manual work processes required. Further, unexpected waiting time occurs due to the scheduling mistake of the worker, resulting in a productivity reduction.
In the conventional art, the resultant periods of machining time, cutting time, etc. are only collected during actual machining. Machining information on what should be done at what hour and minute is not provided. It is an object of the present invention to improve the working efficiency at machining sites, where one worker is responsible for a plurality of machine tools, by providing the worker machining information on what should be done at what hour and minute. Moreover, the present invention allows several workers to be responsible for a multiplicity of machine tools by specifying work items and times of day, thereby further improving the working efficiency as compared to an instance where responsibility is fixed with enhanced schedule flexibility.
In the conventional maintenance time warning system, a warning is given and machine operation is limited when a certain maintenance and inspection item has reached its maintenance and inspection time so that the practice of maintenance and inspection is encouraged. In actual machine maintenance and inspection work, however, preparatory work and secondary maintenance and inspection work may be required to carry out one maintenance and inspection item. For example, the replacement of a spindle belt calls for the preparatory work of ordering the spindle belt and the secondary inspection work of readjusting tension after 10 hours of operation after the belt replacement. The conventional maintenance time warning cannot provide the worker with sufficient maintenance and inspection work schedule information because such preparatory work and secondary maintenance and inspection work cannot be controlled in connection with the maintenance items.
It is another object of the present invention to provide the worker with sufficient maintenance and inspection work schedule information by controlling the maintenance items in connection with the preparatory work and secondary maintenance and inspection work.
Further, for items such as lubricant tank oil level check and chuck lubrication, some of the maintenance and inspection work has a short inspection interval, e.g., about eight hours. With respect to such maintenance and inspection items, the conventional maintenance time warning identifies the remaining time until the maintenance and inspection work must be carried out. In some operation schedules, however, the current time of day plus the remaining time up to the maintenance and inspection work is not always the scheduled time of day for the maintenance and inspection. For this reason, scheduled maintenance and inspection time of day cannot be pre-announced correctly.
It is further object of the present invention to provide a numerical control unit and method of unit operation which pre-announces scheduled maintenance and inspection time of day with high accuracy in consideration of an operation schedule.